Preparation

For the brownie:
Preheat oven to 350ºF. Butter a round cake pan (9 by 1 ½ inch pan) and set to the side.

Melt butter and cocoa powder in the microwave, very slowly. You will want the cocoa to completely blend with the butter until it is smooth. When it’s silky, add sugar, Nutella and melted chocolate. Whisk in eggs. Add flour and salt. Fold. Make sure there are no lumps! Pour into cake pan and bake for 30 minutes.

When it is done, take it out of the oven and allow to cool for at least 2 hours. In the meantime, prepare the Nutella mousse.

For the mousse:
In a medium size steel bowl, add heavy cream, espresso power and hazelnut extract. Whisk until the espresso powder is dissolved. Add Nutella and, using an electric beater, whisk until soft peaks form; this should take around 2-3 minutes. Do not overbeat though. Cover the bowl and refrigerate for 2 hours. Prepare the Nutella glaze now.

For the glaze:
Add powdered sugar, Nutella and milk to a medium size bowl. Whisk together until smooth. Now melt the chocolate for the drizzle.

For the drizzle:
Prepare a double boiler filled with an inch of water and melt chocolate slowly until smooth. Set aside.

For the toasted hazelnuts:
After blanching and toasting the hazelnuts, roughly chop them and set aside.

To assemble the cake:
First start off with the cooled Nutella brownie. Using a serrated knife carefully cut the brownie into 2 layers. Set one layer aside, leaving the other bottom layer where you will fully prepare and present it when it is done.

Take the Nutella mousse out of the refrigerator and spoon onto the bottom brownie layer. It should flow over the whole cake. Using a spatula spread over the brownie, leaving an inch or so of the edges of the brownie bare (when you put the final brownie layer on top, it will naturally push some of the mousse further.)

Drizzle 1 ounce of the chocolate drizzle over the mousse layer.

Carefully put the top brownie layer over the mousse layer. Drizzle the rest of the melted chocolate over the top layer. Pour the glaze over the top brownie layer and spread evenly. Let is drip over the sides of the cake.

Last but not least, sprinkle the chopped hazelnuts over the top of the cake. Buon Appetito!